In a wireless communication system, a base station (BS) generally provides services to a plurality of user equipments (UEs). The BS schedules user data for the plurality of UEs, and transmits control information together with the user data. The control information contains scheduling information for the user data. A channel for carrying the control information is generally referred to as a control channel. A channel for carrying the user data is generally referred to as a data channel. The UE monitors the control channel to search control information of the UE, and processes data of the UE by using the control information.
In order for the UE to receive the user data allocated to the UE, the control information for the user data on the control channel must be received. In general, a plurality of pieces of control information of the plurality of UEs are multiplexed within one transmission interval in an assigned bandwidth. That is, to provide a service to the plurality of UEs, the BS multiplexes the plurality of pieces of control information of the plurality of UEs and transmits the control information on a plurality of control channels. Each UE searches its own control channel among the plurality of control channels.
Blind detection is one of schemes for detecting specific control information among a plurality of pieces of multiplexed control information. The blind detection implies attempting by the UE to recover a control channel by combining a plurality of pieces of information in a state where information required to recover the control channel does not exist. That is, in a state where the UE neither knows whether a plurality of pieces of control information received from the BS is control information of the UE nor knows in which location the control information of the UE exists, the UE decodes all pieces of provided control information until the control information of the UE is detected. The UE may use its unique information to determine whether the received control information is control information of the UE. For example, when the BS multiplexes control information of each UE, the BS may transmit a unique identifier of each UE by masking the identifier onto a cyclic redundancy check (CRC). The CRC is a code used in error detection. The UE demasks its unique identifier to the CRC of the received control information, and thereafter can determine whether the received control information is control information of the UE by performing CRC checking.
However, when the UE monitors the control channel through CRC error detection, even if the control channel is a control channel of another UE, the CRC error may not be detected and thus a decoding result may be erroneously informed that decoding is successful. In case of semi-persistent scheduling (SPS), incorrect CRC error detection becomes more problematic. This is because, in the SPS, the UE receives control information for allocating radio resources and thereafter transmits or receives data by using the radio resources allocated using the control information during an SPS interval. This results in waste of limited radio resources and deterioration in reliability of wireless communication. Accordingly, there is a need for a method for detecting control information with an increased accuracy.